BaseChatPromptTemplate Class — langchain Architecture

Architecture documentation for the BaseChatPromptTemplate class in chat.py from the langchain codebase.

Class python

Entity Profile

Dependency Diagram

graph TD
  93017235_36b7_3b85_820e_aa7d145183e5["BaseChatPromptTemplate"]
  dddce6a3_2420_c71d_01fe_f214c3eb2503["BasePromptTemplate"]
  93017235_36b7_3b85_820e_aa7d145183e5 -->|extends| dddce6a3_2420_c71d_01fe_f214c3eb2503
  d735cdf0_4dd6_b10d_3d65_7f753809639d["chat.py"]
  93017235_36b7_3b85_820e_aa7d145183e5 -->|defined in| d735cdf0_4dd6_b10d_3d65_7f753809639d
  4fe4513e_3354_db06_9595_6bda41c81ffa["lc_attributes()"]
  93017235_36b7_3b85_820e_aa7d145183e5 -->|method| 4fe4513e_3354_db06_9595_6bda41c81ffa
  08b4874f_15ee_e20e_22dd_dc40f35fb150["format()"]
  93017235_36b7_3b85_820e_aa7d145183e5 -->|method| 08b4874f_15ee_e20e_22dd_dc40f35fb150
  a2b4f8ac_2b89_d468_ad91_8d0355c8d508["aformat()"]
  93017235_36b7_3b85_820e_aa7d145183e5 -->|method| a2b4f8ac_2b89_d468_ad91_8d0355c8d508
  e9411289_e300_3889_9890_8b2d1e616969["format_prompt()"]
  93017235_36b7_3b85_820e_aa7d145183e5 -->|method| e9411289_e300_3889_9890_8b2d1e616969
  54d4332a_99bc_4cc5_b549_4f0b0cddfb16["aformat_prompt()"]
  93017235_36b7_3b85_820e_aa7d145183e5 -->|method| 54d4332a_99bc_4cc5_b549_4f0b0cddfb16
  9e40405f_9251_5a40_24a2_2959e7b39db7["format_messages()"]
  93017235_36b7_3b85_820e_aa7d145183e5 -->|method| 9e40405f_9251_5a40_24a2_2959e7b39db7
  888559a1_7b1d_0bba_1c91_f63624147a91["aformat_messages()"]
  93017235_36b7_3b85_820e_aa7d145183e5 -->|method| 888559a1_7b1d_0bba_1c91_f63624147a91
  47fe42aa_c8e0_87b2_ad04_4343c7ef26cb["pretty_repr()"]
  93017235_36b7_3b85_820e_aa7d145183e5 -->|method| 47fe42aa_c8e0_87b2_ad04_4343c7ef26cb
  418ca2f5_d22d_00d9_07a1_bc3639de0847["pretty_print()"]
  93017235_36b7_3b85_820e_aa7d145183e5 -->|method| 418ca2f5_d22d_00d9_07a1_bc3639de0847

Relationship Graph

Source Code

libs/core/langchain_core/prompts/chat.py lines 690–776

class BaseChatPromptTemplate(BasePromptTemplate, ABC):
    """Base class for chat prompt templates."""

    @property
    @override
    def lc_attributes(self) -> dict:
        return {"input_variables": self.input_variables}

    def format(self, **kwargs: Any) -> str:
        """Format the chat template into a string.

        Args:
            **kwargs: Keyword arguments to use for filling in template variables in all
                the template messages in this chat template.

        Returns:
            Formatted string.
        """
        return self.format_prompt(**kwargs).to_string()

    async def aformat(self, **kwargs: Any) -> str:
        """Async format the chat template into a string.

        Args:
            **kwargs: Keyword arguments to use for filling in template variables in all
                the template messages in this chat template.

        Returns:
            Formatted string.
        """
        return (await self.aformat_prompt(**kwargs)).to_string()

    def format_prompt(self, **kwargs: Any) -> ChatPromptValue:
        """Format prompt.

        Should return a `ChatPromptValue`.

        Args:
            **kwargs: Keyword arguments to use for formatting.
        """
        messages = self.format_messages(**kwargs)
        return ChatPromptValue(messages=messages)

    async def aformat_prompt(self, **kwargs: Any) -> ChatPromptValue:
        """Async format prompt.

        Should return a `ChatPromptValue`.

        Args:
            **kwargs: Keyword arguments to use for formatting.
        """
        messages = await self.aformat_messages(**kwargs)
        return ChatPromptValue(messages=messages)

    @abstractmethod
    def format_messages(self, **kwargs: Any) -> list[BaseMessage]:
        """Format kwargs into a list of messages.

        Returns:
            List of `BaseMessage` objects.
        """

    async def aformat_messages(self, **kwargs: Any) -> list[BaseMessage]:
        """Async format kwargs into a list of messages.

        Returns:
            List of `BaseMessage` objects.
        """
        return self.format_messages(**kwargs)

    def pretty_repr(
        self,
        html: bool = False,  # noqa: FBT001,FBT002
    ) -> str:
        """Human-readable representation.

        Args:
            html: Whether to format as HTML.

        Returns:
            Human-readable representation.